The ATLAS Student Event Challenge

The ASEC (ATLAS Student Event Challenge) is an educational project which allows the students to learn about the elementary particles by studying "events", the products of beam collisions at the LHC. The events are collected by the ATLAS detector and displayed graphically using the ATLANTIS package. The students are given the means to select and analyse the events on-line, and subsequently present the results and draw conclusions

Extended Modified Observable Technique for a Multi-Parametric Trilinear Gauge Coupling Estimation at LEP II

This paper describes the extension of the Modified Observables technique in estimating simultaneously more than one Trilinear Gauge Couplings. The optimal properties, unbiasedness and consistent error estimation of this method are demonstrated by Monte Carlo experimentation using $\ell \nu jj$ four-fermion final state topologies. Emphasis is given in the determination of the expected sensitivities in estimating the $\lambda_{\gamma} - \Delta g_{1}^{z}$ and $\Delta k_{\gamma} - \Delta g_{1}^{z}$ pair of couplings with data from the 183 GeV LEPII run.Comment: (17 pages, 8 figures

Muon Energy Loss Upsteam of the Muon Spectrometer

A method for the estimation of the muon energy loss downstream of the Muons Spectrometer is presented. The method provides an improved and updated parametrization of the muon energy loss in ATLAS, along with an estimation based on the actual energy deposition in the calorimeters. The latter aims to account, on an event-by-event basis, for the statistical fluctuations of the energy loss. The final implementation of the presented method combines both the energy loss parametrization and the calorimeter information. This hybrid method provides on average a 5% improvement on the muon stand-alone momentum resolution, reaching 10% for , and reduces the non-gaussian tails. The method is implemented inside the ATHENA framework, in the MuidCaloEnergyTools package

Accurate Estimation of the Trilinear Gauge Couplings Using Optimal Observables Including Detector Effects

This paper describes the definition of maximum likelihood equivalent estimators of the Trilinear Gauge Couplings which include detector effects. The asymptotic properties of these estimators as well as their unbiasedness and efficiency when dealing with finite statistical samples are demonstrated by Monte Carlo experimentation, using simulated events corresponding to the production of q qbar lepton neutrino in e+ e- collisions at 172 GeV. Emphasis is given to the determination of the expected efficiencies in extracting the aWphi, aW and aBphi couplings from LEPII data, which in this particular case found to be close to the maximum possible.Comment: 32 pages, 12 figures, Late

A Method to include Detector Effects in Estimators sensitive to the Trilinear Gauge Couplings

This paper describes the use of weighted Monte Carlo events to accurately approximate integrals of functions of the experimentally measured kinematical vectors and their dependence on physical parameters. This technique is demonstrated in estimating the evolution of cross sections, efficiencies, measured kinematical distributions and mean values as functions of the Trilinear Gauge Couplings.Comment: 20 pages, 10 figures, Late

Multidimensional Binning Techniques for a Two Parameter Trilinear Gauge Coupling Estimation at LEP II

This paper describes two generalization schemes of the Optimal Variables technique in estimating simultaneously two Trilinear Gauge Couplings. The first is an iterative procedure to perform a 2-dimensional fit using the linear terms of the expansion of the probability density function with respect to the corresponding couplings, whilst the second is a clustering method of probability distribution representation in five dimensions. The pair production of W's at 183 GeV center of mass energy, where one W decays leptonically and the other hadronically, was used to demonstrate the optimal properties of the proposed estimation techniques.Comment: (25 pages, 11 figures

The Estimation of the Effective Centre of Mass Energy in q-qbar-gamma Events from DELPHI

The photon radiation in the initial state lowers the energy available for the e$^+$e$^-$ collisions; this effect is particularly important at LEP2 energies (above the mass of the Z boson). Being aligned to the beam direction, such initial state radiation is mostly undetected. This article describes the procedure used by the DELPHI experiment at LEP to estimate the effective centre-of-mass energy in hadronic events collected at energies above the Z peak. Typical resolutions ranging from 2 to 3 GeV on the effective center-of-mass energy are achieved, depending on the event topology.Comment: 12 pages, 6 figure

A PMT-Block test bench

The front-end electronics of the ATLAS hadronic calorimeter (Tile Cal) is housed in a unit, called {\it PMT-Block}. The PMT-Block is a compact instrument comprising a light mixer, a PMT together with its divider and a {\it 3-in-1} card, which provides shaping, amplification and integration for the signals. This instrument needs to be qualified before being assembled on the detector. A PMT-Block test bench has been developed for this purpose. This test bench is a system which allows fast, albeit accurate enough, measurements of the main properties of a complete PMT-Block. The system, both hardware and software, and the protocol used for the PMT-Blocks characterisation are described in detail in this report. The results obtained in the test of about 10000 PMT-Blocks needed for the instrumentation of the ATLAS (LHC-CERN) hadronic Tile Calorimeter are also reported.Comment: 23 pages, 10 figure

Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13